It is an aim of the invention to provide a saw-tooth clothing of the kind described at the beginning which avoids or mitigates the mentioned disadvantages and which, especially, retains a high level of aggressiveness over its lifetime.
The invention provides a saw-tooth clothing for rollers of flat cards or roller cards, having an elongate foot region and an adjoining blade in which teeth have been formed by cutting, which teeth have a tooth front, a tooth back and two side flanks, wherein the tooth front has a first portion extending from the tooth tip and a second portion extending from said first portion towards the foot region and the first portion of the tooth front is substantially convex.
The first portion of the tooth front is substantially convex in the direction towards the tooth back of the adjacent tooth (that is, the tooth back on the opposite side of the adjacent gullet). In practice, therefore, the first portion of the tooth front is preferably convex, or approximately convex, in the direction of movement of the clothing.
Because the first portion of the tooth front is convex in the direction of movement of the clothing, the wear-induced reduction in the front angle may be lessened or the front angle may remain the same or even be enlarged. As a result, the loss of aggressiveness caused by the non-resharpenable rounded-off tooth flanks and by the wear-induced reduction in the front angle α can be mitigated or compensated for. The quality of the product produced is accordingly subject to less fluctuation.
In practice that is achievable as a result of the resharpening of the tooth that is customary for cylinder and roller card clothings. In that procedure, the tooth tip is ground from the top until a sharp working edge is formed again at the tip. The reduction in height that occurs each time the clothing is ground causes the resulting tooth tip on the tooth front to migrate a little further downwards each time. In the case of the invention, because of the special shape of the tooth, that results in principle in an increase in the front angle. The wear-induced reduction in the face angle customary in cylinder and roller card clothings is thus lessened or does not occur.
Advantageously, the second portion of the tooth front is concavely or approximately concavely curved in the direction of movement of the clothing.
In certain preferred embodiments, the first portion is arcuately curved. Advantageously, the first portion merges into the second portion.
In use of the clothing of the invention, the wear-induced reduction in the working angle (front angle) is lessened. In certain embodiments, the working angle (front angle) remains the same on wear. In other embodiments, the working angle (front angle) becomes greater on wear. Preferably, the reduction or enlargement or retention of the working angle (front angle) is effected after resharpening of the clothing. Preferably, the clothing is an all-steel clothing.
The invention further provides a flat card or roller card, comprising a roller and/or cylinder on which is mounted a saw-tooth clothing constructed in accordance with the invention.
The invention also provides a saw-tooth all-steel clothing for rollers and/or cylinders of flat cards or roller cards, having an elongate foot region (foot) and an adjoining tooth region (blade) in which teeth have been formed by cutting, which teeth have a tooth front, a tooth back and two side flanks, wherein between the tooth back and the tooth front of two teeth arranged one after the other there is a gullet and the teeth consist of at least two portions, with a first portion, located at a tooth tip, having a positive or at least perpendicular working angle (front angle) and the spacing between the tooth tip and the transition region between the first and the second portions forming a technologically effective region, wherein the first portion of the tooth front is convex or approximately convex in the direction of movement of the clothing.